Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 250455
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1155 PM CDT TUE MAR 24 2015

.UPDATE...
ISSUED AT 530 PM CDT TUE MAR 24 2015

HAVE ADDED ISOLATED THUNDER TO THE FORECAST THIS EVENING MAINLY
ALONG AND SOUTH OF IA 92. TSRA HAS BEEN REPORTED IN CONJUNCTION
WITH THE SHORTWAVE CROSSING THE MO RIVER VALLEY...WITH LIGHTNING
STRIKES OBSERVED WITH THE CELLS IN SOUTHEAST NE AND NORTHWEST MO
LIFTING NORTHEAST. ATTM INSTABILITY IS EXPECTED TO NOT BE HIGH
ENOUGH FOR THUNDER NORTH OF IA 92.

&&

.SHORT TERM /TONIGHT/...
ISSUED AT 241 PM CDT TUE MAR 24 2015

TWO MAIN AREAS OF PRECIP TO BE CONCERNED ABOUT WITH THE UPPER LEVEL
WAVES MOVING THROUGH THE REGION. SOUTHERN STREAM SHORTWAVE
RESPONSIBLE FOR PRECIP AREA PUSHING THROUGH SOUTHERN AND CENTRAL
IOWA TODAY AND SHOULD CONTINUE TO PUSH EAST NORTHEAST. LOTS OF DRY
AIR HAD BEEN IN PLACE...SO PRECIP WAS FIGHTING IT ALL DAY AND THUS
HAS HAD A HARD TIME LIFTING TOO FAR NORTH. ADDITIONALLY THIS HAS
KEPT TEMPS DOWN AND THERE HAVE HAD MORE PATCHES OF FZRA REPORTED
ACROSS MUCH OF THE CENTRAL AND SOUTHERN CWA. THIS TREND MAY CONTINUE
WITH THE NORTHERN EXTENT OF THE PRECIP AREA...WITH SOUTHERN COUNTIES
WARMING UP ENOUGH FREEZING TO HAVE ALL RAIN THROUGH THE LATTER
PORTION OF THE AFTERNOON. COLDER AIR TO MOVE IN HOWEVER WITH THE
COLUMN COOLING ACROSS THE WEST/NORTH AS THE NORTHERN STREAM SHORTWAVE
ROTATING AROUND THE UPPER LOW ACROSS THE NORTHERN PLAINS. THIS WILL
BRING THE SECOND AREA OF PRECIPITATION THROUGH THE CWA BY LATE
AFTERNOON INTO THE EVENING HOURS. THIS AREA CURRENTLY ACROSS NW
IA/SE SD/ERN NE. SOUNDINGS INDICATE MAJORITY OF THIS PRECIPITATION
MAY INITIAL BEGIN AS RAIN BUT WILL QUICKLY TRANSITION TO SNOW ALONG
AND NORTH OF HWY 20 AND EVEN SOME SNOW MIXING IN AT TIMES ALONG THE
HWY 30/I80 CORRIDORS THIS EVENING. LIGHT SNOW ACCUMULATIONS STILL
EXPECTED WITH AROUND 2-3 INCHES ACROSS THE NORTHERN THIRD OF THE
CWA...WITH A FEW ISOLATED HIGHER AMOUNTS POSSIBLE IF GET SOME
CONVECTIVE STRUCTURE. OVERALL THOUGH INSTABILITY NOT AS GREAT AS
PREVIOUSLY THOUGH ESPECIALLY ACROSS THE SOUTH...SO HAVE REMOVED ALL
THUNDER MENTION FOR NOW.

.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
ISSUED AT 241 PM CDT TUE MAR 24 2015

MAIN CHALLENGES THIS PERIOD WILL BE SEVERAL WEAK SHORT WAVES
APPROACHING THE REGION THROUGH EARLY NEXT WEEK AND THEN THE
HINT OF A STRONGER SYSTEM EJECTING OUT OF THE ROCKIES BY TUESDAY
AND WEDNESDAY. SPLIT FLOW FEATURES THE SOUTHERN STREAM WAVE
CURRENTLY AFFECTING IOWA WITH A SECONDARY WAVE OVER THE WESTERN
DAKOTAS AT 12Z...EXPECTED TO MOVE NORTHEAST TOWARD DULUTH BY 12Z
WEDNESDAY. THIS WILL EVENTUALLY PULL A COLD FRONT SOUTHEAST THROUGH
THE AREA BY WED NIGHT AND BRING CLEARING BACK WITH SOME SUNSHINE
FOR THURSDAY. THIS SHOULD BEGIN TO MELT ANY SNOW OR ICE WHICH
FALLS THROUGH TONIGHT. H850 TEMPS ACTUALLY BRIEFLY WARM TO 4 TO
6C FOLLOWING THE LOW PASSAGE ON WEDNESDAY JUST PRIOR TO THE COLD
FRONT ARRIVING IN THE AFTERNOON HOURS. THOUGH FRONT WILL GENERALLY
LACK IN MOISTURE...EXPECT TO SEE SOME LIGHT PRECIPITATION ALONG
THE EXITING BOUNDARY AS UPPER LEVEL FRONT PROVIDES SOME LIFT ALONG
THE WAY. WILL EXPAND POPS ACROSS THE SOUTH ON WEDNESDAY AND BEGIN
EARLIER AS WELL OVER THE WEST. HIGHS THOUGH TOMORROW RECOVER
MAINLY DUE TO WESTERLY FLOW DURING THE DAY. AFTER THE SYSTEM
DEPARTS...NORTHWEST WINDS WILL SCOUR MOISTURE OUT OF THE AREA AND
CLEAR SKIES SHOULD RETURN. WINDS WILL BE GUSTY BEHIND THE BOUNDARY
WED EVENING BUT WILL REMAIN BELOW WIND ADY CRITERIA. ALL MODELS
PROG A SECONDARY CANADIAN COLD FRONT WHICH WILL DRIVE SOUTH BY 12Z
FRIDAY. THIS WILL LOWER H850 TEMPS TO -10C TO -16C NORTHEAST BY
MIDDAY...AND HIGHS WILL RESPOND DOWNWARD ACCORDINGLY. BUFR
SOUNDINGS SHOW THAT...THOUGH WE DONT HAVE ENOUGH MOISTURE AROUND
TO PROMOTE STRATUS OVERCAST...LIKELY WELL SEE FEW TO SCT CUMULUS
FRIDAY WITH INCREASE IN SOIL MOISTURE DUE TO TODAYS EVENT AND
STRONG COLD AIR ADVECTION. SO...WILL KEEP HIGHS NEAR EXPECTED MIN
MAX RANGE...IN THE 30S NORTHEAST TO THE LOWER 40S CENTRAL AND
SOUTH. OTHERWISE FRIDAY LOOKS LIKE A PLEASANT DAY. BY FRIDAY
AFTERNOON A WEAK CLIPPER WILL MOVE SOUTHEAST WITH THE NORTHWEST
FLOW AND JUST BRUSH THE WESTERN COUNTIES WITH SOME LIGHT SNOW AS
WARM AIR ADVECTION RETURNS. WITH THE WESTERN RIDGE COLLAPSING AND
ZONAL FLOW RETURNING...MUCH WARMER H850 TEMPS WILL BEGIN
TRANSITIONING TOWARD THE REGION. FROM FRIDAY AFTERNOON THROUGH
SUNDAY H850 TEMPS WILL WARM FROM -8C TO 10C WITH WESTERLY FLOW
ALOFT. THUS... TEMPERATURES WILL WARM NICELY SATURDAY AND SUNDAY
OVER A GOOD SHARE OF THE FORECAST AREA. BREEZY CONDITIONS SHOULD
ACCOMPANY THE SUNDAY WARM UP AS WELL. ANOTHER COLD FRONT WILL DROP
SOUTH BY MONDAY WITH A BRIEF COOL OFF BEFORE ANOTHER WARM UP
ARRIVES FOR TUESDAY INTO WEDNESDAY. THERE IS ALSO A HINT THAT
INSTABILITY WILL BE INCREASING TOWARD MIDWEEK AS THE SHORTWAVE
ARRIVES INTO THE PLAINS. HIGHS BY LATE IN THE EXTENDED MAY BE WELL
INTO THE 70S BY LATE IN THE DAY.

&&

.AVIATION...25/06Z
ISSUED AT 1139 PM CDT TUE MAR 24 2015

WIDESPREAD IFR WITH POSSIBLE BRIEF LIFR CIGS WILL PERSIST
OVERNIGHT...EVEN WITH PRECIPITATION MOVING OUT OF THE REGION.
FOG MAY DEVELOP IN AREAS WHERE WINDS GO LIGHT...BUT NOT EXPECTED
TO BE WIDESPREAD AND PERSISTENT WITH MIXING FROM 5 TO 8KT WINDS.
CIGS AND VISIBILITIES WILL GO VFR LATE MORNING TO EARLY
AFTERNOON...WORKING EASTWARD...AS REMNANTS OF TONIGHTS SYSTEM GET
PUSHED OUT OF THE REGION.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 1 AM CDT WEDNESDAY FOR BREMER-
BUTLER-CERRO GORDO-FRANKLIN-HANCOCK-WINNEBAGO-WORTH-WRIGHT.

&&

$$

UPDATE...ZOGG
SHORT TERM...BEERENDS
LONG TERM...REV
AVIATION...CURTIS



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